Hostname: page-component-848d4c4894-wzw2p Total loading time: 0 Render date: 2024-05-16T13:02:52.263Z Has data issue: false hasContentIssue false

Passive control of jet flows using lobed nozzle geometries

Published online by Cambridge University Press:  11 July 2007

Ilinca Nastase
Affiliation:
LEPTAB, University of La Rochelle, Avenue Michel Crépeau 17042 La Rochelle Cedex 01, France
Amina Meslem
Affiliation:
LEPTAB, University of La Rochelle, Avenue Michel Crépeau 17042 La Rochelle Cedex 01, France
Get access

Abstract

Passive control of the entrainment phenomenon in the turbulent jets is a mixing enhancement economical method of wide interest in the industrial field. A lobed nozzle without lobes inclinations allows improving mixing in the generated flow compared to a reference circular jet. A second lobed nozzle, having the same exit plane geometry but with inclined lobes intensifies, in a considerable manner, the entrainment which reaches up to four times the one in the reference circular jet. The lobed jets vortical dynamics analysis shows that the azimuthal structures are not annular like in the case of a circular jet, but discontinuous, due to the shear of the transverse flow induced by the curvature variation of the exit plane. The streamwise structures development at the discontinuities locations is probably explaining the entrainment benefit observed in the lobed jet without inclination angles. The lobed jet issued from the second nozzle presents like the first lobed jet, discontinuous azimuthal structures, but its remarkable induction benefit is not merely owed to the previous phenomenon. The intensification and organisation of the streamwise vorticity field into large scale structures, resulting in a consequent mixing enhancement, are connected to the increased shear produced by the lobes inclinations.

Type
Research Article
Copyright
© AFM, EDP Sciences, 2007

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Zaman, K.B.M.Q., Hussain, A.K.M.F., Vortex pairing in a circular jet under controlled excitation, Part 1, General response, J. Fluid Mech. 101 (1980) 449441 CrossRef
Hussain, F., Hussain, H.S., Elliptic jets, Part 1, Characteristics of unexcited and excited jets, J. Fluid Mech. 208 (1989) 257320 CrossRef
Lin, Y.T., Shich, M.S., Liou, H.D., Hou, C.S., Investigation on the mass entrainment of an acoustically controlled elliptic jet, Inter. Comm. Heat and Mass Transfer 25 (1998) 379388 CrossRef
Sfeir, A.A., Investigation of three-dimensional turbulent rectangular jets, AIAA J. 17 (1979) 10551060 CrossRef
Quinn, W.R., Development of a large-aspect-ratio rectangular turbulent free jet, AIAA J. 32 (1994) 547554 CrossRef
Ho, C.M., Gutmark, E., Vortex induction and mass entrainment in a small-aspect–ratio elliptic jet, J. Fluid Mech. 179 (1987) 383-405 CrossRef
K.B.M.Q. Zaman, Spreading characteristics and thrust of jets from asymmetric nozzles, AIAA (1996) 1–17
Hu, H., Kobayashi, T., Wu, S., Shen, G., Changes to the vortical and turbulent structure of jet flows due to mechanical tabs, Proc. Instn. Mech. Engrs. 213 (1999) 321329
Belovich, V.M., Samimy, M., Mixing processes in a coaxial geometry with a central lobed mixer-nozzle, AIAA J. 35 (1997) 838841 CrossRef
H. Hu, T. Kobayashi, T. Saga, S. Sagawa, N. Taniguchi, Particle image velocimetry and planar laser-induced fluorescence measurements on lobed jet mixing flows, Experiments in Fluids (2000) S141–S157
Hu, H., Saga, T., Kobayashi, T., Taniguchi, N., Research on the vortical and turbulent structures in the lobed jet flow using laser induced fluorescence and particle image velocimetry techniques, Measurement Science and Technology 11 (2000) 698711 CrossRef
Hussain, A.K.M.F., Zaman, K.B.M.Q., The preferred mode of the axisymmetric jet, J. Fluid Mech. 110 (1981) 3971 CrossRef
Jeong, J., Hussain, F., On the identification of a vortex, J. Fluid Mech. 285 (1995) 6994 CrossRef
Liepmann, D. and Gharib, M., The role of streamwise vorticity in the near-field entrainment of round jets, J. Fluid Mech. 245 (1992) 643668 CrossRef